Multi-walled Carbon Nanotubes Content Research Articles

Nutrient removal from biogas slurry and biogas upgrading by microalgae-fungi-bacteria co-cultivation under different carbon nanotubes concentration.

In this study, Chlorella vulgaris, Ganoderma lucidum, and endophytic bacteria were co-cultivated with the stimulation of strigolactone analogs GR24 to prepare pellets. During the purification of biogas slurry and biogas, multi-walled carbon nanotubes (MWCNTs) were introduced to enhance the removal efficiencies of nutrients and CO2. The results showed that both GR24 and MWCNTs affected the purification of biogas slurry and biogas. The maximum chemical oxygen demand, total nitrogen, total phosphorus, and CO2 removal efficiencies of the Chlorella vulgaris-Ganoderma lucidum-endophytic bacterial symbionts were 82.57 ± 7.96% (P < 0.05), 82.14 ± 7.87% (P < 0.05), 84.27 ± 7.96% (P < 0.05), and 63.93 ± 6.22% (P < 0.05), respectively, with the induction of 10-9M GR24 and 1mg L-1 MWCNTs. Moreover, the growth and photosynthetic performance of the symbionts were consistent with the removal effects. The Chlorella vulgaris-Ganoderma lucidum-endophytic bacterial symbionts obtained high growth rates and enzyme activity with the maximum growth rate of 0.365 ± 0.03d-1, mean daily productivity of 0.182 ± 0.016g L-1 d-1, and carbonic anhydrase activity of 31.07 ± 2.75 units, respectively. These results indicated that an appropriate concentration of GR24 and MWCNTs could promote the growth of symbionts, reinforce the purification effects of biogas slurry and biogas, and provide a new idea for the simultaneous purification of wastewater and biogas.

Combination of enhanced strength-ductility trade-off and stress relaxation resistance of MWCNTs reinforced Sn–5Sb-0.3Cu matrix composite

In this study, the strength-ductility trade-off and stress relaxation (SR) behavior of Sn–5Sb-0.3Cu (SSC503) alloy reinforced with (0, 0.05and 0.1 wt%) multi-walled carbon nanotubes (MWCNT) have been investigated under different pre-strains and initial stress levels. The results show that the pre-deformation can extend the duration of initial SR stage and significantly promote the stress reduction rate. The SSC503–0.05MWCNT composite alloy exhibits the optimum increase in SR resistance, yield strength (σy), ductility, and creep threshold stresses with the values of 75.8%, 17.3%, 77.9% and 10.6%, respectively. The scanning transmission electron microscopy (STEM) images and electron probe microanalyzer (EPMA) revealed that the distribution of MWCNT in SSC503 alloy was concentration dependent. 0.05MWCNT concentration induced a dendritic/cellular transition of β-Sn grains and restrained the growth of β-Sn, Cu6Sn5, SnSb, Sn3Sb2 and Cu2Sb IMC compositions, whereas 0.1MWCNT led to the partial agglomeration of MWCNT into β-Sn grain surfaces. MWCNTs are adsorbed at the surface-active atoms of Sb metalloid to form Sb-coated MWCNTs (Sb/C) in situ, which act as a bridge between MWCNT and Cu6Sn5 particles. The modified composites represent a vital technological progress for utilization in high temperature solder applications.

Multi-scale integrated design and fabrication of ultra-broadband electromagnetic absorption utilizing multi-walled carbon nanotubes-based hierarchical metamaterial

Ultra-broadband electromagnetic absorption has become a critical issue competing with advanced broadband electromagnetic detection systems. In this study, an innovative strategy for the broadband absorption is proposed via combining periodic patterns and the hierarchical structure with gradient electromagnetic performance, which introduces an abnormal electromagnetic response for improved maneuverability in impedance matching and multiple electromagnetic loss mechanisms. The electromagnetic parameters for each layer were determined by the fixing content of multi-walled carbon nanotubes (MWCNTs) in gypsum, and the periodic stepped meta-structure was optimized via the finite element simulation. The optimized hierarchical MWCNTs/gypsum metamaterial with a thickness of 8.0 mm realized an average absorption intensity of −21.6 dB (>99.3% absorption) in the frequency band of 4–40 GHz. Particularly, broadband EM absorption for reflection loss less than −10 dB and −15 dB was achieved in the ranges of 4.2–40 GHz and 5.6–40 GHz, respectively. The ultra-broadband and strong electromagnetic absorption properties of the proposed metamaterial should be the synergic result of the excellent impedance matching and the multiple EM wave loss caused by the multi-scale integrated structure. Therefore, the proposed MWCNTs/gypsum metamaterial with the innovative strategy of combining the hierarchical structure and periodic patterns, could provide an insight for achieving high-performance absorption materials.

A novel carbon nanotubes doped natural rubber nanocomposite with balanced dynamic shear properties and energy dissipation for wave energy applications

Mechanical characterizations of natural rubber filled with carbon-based nanomaterials were extensively studied in tensile and tear modes whereas fewer attempts have been conducted on a dynamic shear condition using a double-bonded shear test piece. This is of importance since natural rubbers are widely used as flexible membranes for wave energy harvesting devices. Therefore, this study was aimed to explore the microstructural, rheological, and dynamic viscoelastic characteristics of natural rubbers filled with different Multi-Walled Carbon Nanotubes (MWCNTs) contents. A combined compounding approach was employed to ensure a homogenous CNT dispersion was achieved. Transmission electron microscopy (TEM) was performed for the materials characterization while the processability and curing parameters of the compounds were investigated using the Mooney viscosity and rheometry test. Dynamic shear properties were compared using a cyclic test performed on a double-bonded shear test piece. TEM images showed that an optimum CNTs dispersion was reached at 3 phr MWCNTs loading whereas increasing CNT content resulted in further inhomogeneity. The addition of CNTs into the natural rubber not only improved the curing properties of the compound, i.e., low scorch and curing times, but it also increased the Mooney viscosity, the rheological properties, and the dynamic shear properties of the nanocomposite compared to the pristine rubber. The Payne and Mullins effects were also observed for all compounds manifesting dependency on the CNTs content and applied strain amplitude. Finally, MWCNT enhanced the dissipated energy of the nanocomposites with respect to the neat rubber in which an increase of 1040 % in energy dissipation for 10 phr MWCNTs compared to the control at a strain amplitude of 200 % was achieved.

Development of nanomodified self-healing mortar and a U-Net model based on semantic segmentation for crack detection and evaluation

In this study, a cement-based self-healing (SH) mortar mixed with multiwalled carbon nanotubes (MWCNTs) was developed, and the effect of MWCNT addition on the electromechanical properties of mortar was studied. In addition, a deep learning based U-shaped Network (U-Net) model was adopted for the crack healing evaluation in SH mortar specimens. The trained U-net model is capable to detect the cracks with the accuracy of 99 %. The MWCNT content in the mortar was varied from 0.05 % to 0.10 % by weight of the cement. A minerals-based SH admixture was incorporated at concentrations of 2.5 %, 5 %, and 7.5 % by weight of cement. Compression and flexural strength tests were performed to investigate the mechanical performance of the nanomodified mortar. Piezoresistive sensing properties of MWCNT/cement composite were monitored during flexural test. For crack healing evaluation, cracked mortar prisms were exposed to water for 28 days. Mechanical and piezoresistive sensing evaluation demonstrated improved mechanical performance of SH mortar with appreciable self-sensing properties. Specimens with 2.5 % admixture exhibited a crack sealing efficiency of approximately 90 %, while the cracks in specimens with 5 % and 7.5 % SH admixture content healed 100 % after 28 days of water exposure.

Effect of multi-walled carbon nanotubes on durability of high-strength slag-based geopolymer

The effect of multi-walled carbon nanotubes (MWCNTs) on the durability of high-strength slag-based geopolymers was investigated. The control variables were the MWCNT content and MWCNT/dispersant and water-cement ratios. A total of 144 specimens were exposed to carbonization, freeze-thaw cycles, and chloride migration (RCM). The microstructure of the geopolymers before and after durability testing was observed using scanning electron microscopy (SEM). The modification of pore structure of geopolymer by MWCNTs was measured by mercury intrusion porosimetry (MIP). The composition of the materials was analyzed using X-ray diffraction (XRD), and the contents of the materials were determined quantitatively using thermal gravimetric analysis (TG). When the MWCNT content and water-cement and MWCNTs/sodium dodecyl sulfonate (SDS) ratios were 0.45 wt%, 0.55, and 2.5:1, respectively, the carbonization depth and carbonization strength of the geopolymers were 69% and 176% of those the control group, respectively. The loss rate and relative dynamic elastic modulus after freeze-thaw were 28% and 121% of those of the control group, respectively. The Cl− diffusion depth and diffusion coefficient were 63% and 84% of those of the control group, respectively. Water-cement ratio affected the internal structure and crystallinity of geopolymer. MWCNTs mixed with SDS to modify geopolymers, the main function of MWCNTs was to densify the matrix and improve the internal cracks and pores. However, the excess SDS caused structural foaming and reduced the durability of the geopolymer.

The effects of multiwalled carbon nanotubes and Bacillus subtilis treatments on the salt tolerance of maize seedlings.

Nanomaterials, including multiwalled carbon nanotubes (MWCNTs), have been recently applied in agriculture to improve stress resistance, leading to contradictory findings for antioxidant responses and mineral nutrient uptake. A pot experiment involving maize in low-salinity sandy loam soils was conducted with the application of different concentrations (0, 20, 50 mg/L) of MWCNTs and the growth-promoting rhizobacterium Bacillus subtilis (B. subtilis). The dose-dependent effects of MWCNTs were confirmed: 20 mg/L MWCNTs significantly promoted the accumulation of osmolytes in maize, particularly K+ in the leaves and roots, increased the leaf indoleacetic acid content, decreased the leaf abscisic acid content; but the above-mentioned promoting effects decreased significantly in 50 mg/L MWCNTs-treated plants. We observed a synergistic effect of the combined application of MWCNTs and B. subtilis on plant salt tolerance. The increased lipid peroxidation and antioxidant-like proline, peroxidase (POD), and catalase (CAT) activities suggested that MWCNTs induced oxidative stress in maize growing in low-salinity soils. B. subtilis reduced the oxidative stress caused by MWCNTs, as indicated by a lower content of malondialdehyde (MDA). The MWCNTs significantly increased the leaf Na+ content and leaf Na+/K+ ratio; however, when applied in combination with B. subtilis, the leaf Na+/K+ ratio decreased sharply to 69% and 44%, respectively, compared to those of the control (CK) group, the contents of which were partially regulated by abscisic acid and nitrate, according to the results of the structural equation model (SEM). Overall, the increased osmolytes and well-regulated Na+/K+ balance and transport in plants after the combined application of MWCNTs and B. subtilis reveal great potential for their use in combating abiotic stress.

The Effect of Multi-Walled Carbon Nanotubes on the Compressive Strength of Cement Mortars

In this work, multi-walled carbon nanotubes (MWCNTs) have been synthesized using a modified method of solid-phase pyrolysis. The MWCNTs are effectively dispersed using a simple and facile method such as ultrasonic energy without and with surfactant for two different sonication times (15 min and 40 min). In the present study, the effect of MWCNT concentration (0.001, 0.01, 0.05, 0.1 wt.%) on the compressive strengths of cement mortars has been investigated. Compressive tests were carried out on an automatic pressure machine (C089) with a loading rate of 0.5 kN/s at the age of 7 days and 28 days. It is shown that the optimal value of the nanotubes’ concentration does not exist in the case of 15 min of sonication time, whereas the optimal value for 40 min of sonication time without and with surfactant is 0.01%. Moreover, in the absence of surfactants, the strength of the specimen over 7 days of hardening increased by 13%, and by 19.5% in the presence of surfactants. The compressive strength for a curing period of 28 days increased by 6.3% and 13.8%, respectively.

Modified carbon nanotubes/polyvinyl alcohol composite electrothermal films

Carbon nanomaterials are ideal materials for electrothermal applications because of their superior thermal conductivity, electrical conductivity, and mechanical properties. Electrothermal composites with excellent performance should have the characteristics of rapid temperature response, uniform heating temperature distribution, and good thermal stability after prolonged heating. However, for previously prepared electrothermal composites still have some shortcomings such as long temperature response time, uneven temperature distribution and poor thermal stability after long time heating. In this study, the composite electrothermal films with excellent performances were obtained by a layer-by-layer deposition approach, which were synthesized by pouring epigallocatechin gallate-functionalized multi-walled carbon nanotubes (E-MWCNTs) into a polytetrafluoroethylene mold and subsequently curing the polyvinyl alcohol (PVA) solution on the CNT layer. The electro-heating behavior of composite electrothermal film with different content and size was investigated by applying various voltages. They exhibit excellent electrothermal property, that is, a rapid temperature response, which can reach the steady-state temperature (TMAX) within 90 s. In addition, the maximum temperature can reach about 140 °C at 12 V. It was observed that the temperature of the composite electrothermal film has no significant change during the cycle tests of various voltages and 5 h aging time. According to the results of the experiment, the electrothermal properties of the composite electrothermal films are affected by the content of multi-walled carbon nanotubes (MWCNTs) and the applied voltage, which means that we can achieve accurate control of its properties by adjusting the content of MWCNTs and the applied voltage. Moreover, we have great expectations that these composite electrothermal films will have broad prospects for thermal management in wearable applications and electro-devices.

Strengthening the bonding interfaces of hybrid titanium carbon laminates by bionic micro texture and carbon nanotube pinning

A reliable strategy to enhance the bonding ability in hybrid titanium carbon laminates (HTCLs) is proposed, which is based on the pinning effect produced by bionic micro texture etched by laser on titanium and multi-walled carbon nanotubes (MWCNTs) introduced into adhesive layer. The characteristic of bionic micro texture is determined, and the strengthening mechanism of bonding interfaces is revealed. The HTCLs samples with various micro texture groove widths, laser scanning times and MWCNTs content are fabricated via an autoclave process. The micro texture morphologies, surface wettability, interlayer bonding properties under different conditions are studied. Results show that the recast layers formed on titanium during etching are beneficial to improve the interfacial bonding properties. Compared with no micro texture, the contact angle with micro texture can be reduced by 68.4%. Both micro texture and MWCNTs can reduce the defects at the interlayer interfaces and improve the interfacial adhesion. In this work, the maximum tensile shear strength (TSS) and interlaminar shear strength (ILSS) can be obtained with the micro texture groove width of 30 μm, the laser scanning of 30 times and the MWCNTs content of 0.4 wt%, which are 56.39% and 32.84% higher than that without any treatment, respectively.

Effect of Recycling on the Mechanical, Thermal and Rheological Properties of Polypropylene/Carbon Nanotube Composites

In this research the effect of physical recycling on the mechanical, thermal, and rheological properties of polypropylene (PP)/multiwalled carbon nanotube (MWCNT) was investigated. After melt homogenization by extrusion, specimens were injection moulded with 0.1 and 0.5 wt% MWCNT content. The recycling process was simulated by multiple grinding and re-moulding, then we compared the behavior of original and recycled PP/MWCNT composites. Differential scanning calorimetry (DSC) measurements proved that MWCNT had double the effect on the morphology of the PP matrix: on the one hand nucleating effect can be detected because 0.5 wt% MWCNT increased the onset temperature of crystallization by 10 °C, compared to the basic PP material; on the other hand, the crystalline fraction of the recycled composite materials decreased compared to the original PP material with the same MWCNT content. This resulted in a slight decrease in strength and stiffness but an increase in elongation at break. However, compared to the original unreinforced PP reference, even the recycled materials have better properties. The mechanical test results showed that recycled PP/MWCNT 0.5 wt% increased the elastic modulus (~15%) and decreased the tensile strain at yield (~10%). However, in the values of tensile stress at yield, relevant difference was not found. It was also shown by oscillatory rheometry that MWCNT had a significant effect on the rheological properties (storage and loss modulus, complex viscosity) of PP compounds in a wide temperature range (190-230 °C).

Thermal and exergy analysis of Pin-finned heatsinks for nanofluid cooled high concentrated photovoltaic thermal (HCPV/T) hybrid systems

• Cooling performance of HCPV/T is systematically investigated. • Different shaped pin-finned heat sinks (inline and staggered) are examined. • Thermal performance is determined for MWCNT nanofluids. • Exergy efficiencies of pin-fin heat sinks in HCPV/T are evaluated. • 2% MWCNT nanoparticle concentration is found to be the optimum. Cooling of High Concentrated Photovoltaic (HCPV) cells is a major concern among researchers due to higher heat generation in the cells from highly concentrated solar radiation. In the present investigation, a numerical study of the High Concentrated Photovoltaic Thermal (HCPV/T) system is conducted for the combined effect of nanofluids and pin-finned heatsinks on the cooling performance. The investigation is carried out for AZUR SPACE solar cell (Model: 3C44C) for 1000 Concentration Ratio (CR) and the Reynolds number ( Re ) varies within the laminar range (600 ≤ R e ≤ 2200). Different shapes of pin-fins and their orientations are systematically investigated for the effect of Multi-walled Carbon Nanotube (MWCNT) nanoparticles in a base fluid. The results show a significant reduction in the temperature (up to 18K) of the solar cells for the MWCNT nanofluid compared to its base fluid counterpart. A higher heat transfer characteristics (Nusselt numbers) and lower average temperature of top surface of HCPV cells are found to occur for the staggered arrangements of pin-fins. It is also noticed that the volume concentration of MWCNT in water affects heat transfer characteristics and reduction in temperature takes place up to the volume concentration of 2%. About 1.3% reduction in temperature is predicted for adding MWCNT nanoparticle concentration from 0.5% to 2%. However, in terms of exergy efficiency, maximum overall exergy (about 67% for water flow rate of 0.00167 kg/s) is found for square pin-fins with inline arrangements. The average increase in Nusselt number from inline to staggered arrangement are around 11%, 74%, and 22% respectively for circular, square and triangular fins. The maximum electrical efficiency reaches to 42.2% for both 2% and 4% MWCNT with staggered circular pin-fins for a mass flow rate of 0.0058kg/s. Finally, it appears that a combination of nanofluids and pin-finned heatsinks gives a better cooling rate in the HCPV/T system and could be a promising alternative along with other cooling techniques.

The effect of acid treated multi-walled carbon nanotubes on the properties of cement paste prepared by ultrasonication with polycarboxylate ester

Chemical functionalization of carbon nanotubes by the mix of sulfuric (H2SO4) and nitric (HNO3) acids has been reported to enhance the hydrophilicity of carbon nanotubes, which, in turn, improves its dispersion quality in aqueous solution and within the cement matrix. In this study, multi-walled carbon nanotubes (MWCNT) were treated by a mix of H2SO4 and HNO3, and used for preparation of MWCNT solutions by ultrasonic tip sonication with low amounts of polycarboxylate ester (PCE). The effects of acid functionalization on the dispersion of MWCNT, mechanical performance and hydration of cement paste were studied with respect to changes in MWCNT concentration, ultrasonication time and MWCNT:PCE ratio. According to the experimental results, acid-treated MWCNT contained 13 wt% of carboxyl functional group. The results from Raman spectroscopy showed the increased amount of unadsorbed PCE in solution with acid-treated MWCNT due to the increase in hydrophilicity. Increase in hydrophilicity contributed to a stronger bond between a-MWCNT and cement hydration products, and increased the mechanical strength of cement paste by 55%. The addition of a-MWCNT at 0.1 wt% concentration resulted in the increase of 28-day compressive strength from 40 MPa up to 62 MPa and flexural strength from 4.4 MPa up to 7.6 MPa. Retardation in hydration and increase in porosity were found to be associated with PCE that was not adsorbed on the surface of MWCNT.

Electromagnetic wave reduction of multiwalled carbon nanotubes (MWCNT) mixed nanometer CoFe2O4 at higher frequency range

Traditional granular electromagnetic wave absorbers such as spinel ferrites are well known because of its high saturation magnetization and electrical resistivity. However, the application of ferrite absorbent as an electromagnetic wave absorber is restricted by their increased in density and poor environmental stability. Thus, multiwalled carbon nanotubes (MWCNTs) were introduced to enhance the electromagnetic wave absorbing performances. Different weight percentages of MWCNTs (0.5 wt%, 2 wt% and 4 wt%) were mixed with nanometer-size CoFe2O4 and being used as fillers (60 wt%), further incorporated into epoxy resin as polymer matrix (40 wt%). The reflectivity and morphological study of the prepared samples were measured at X and Ku-band (8 – 18 GHz). The results reveal that varying the amount of MWCNT content has influence the performance of the processed electromagnetic wave absorber. The reflection loss peak shifted towards a lower frequency for thickness of 1 mm, 2 mm and 3 mm as the MWCNT content increased. The MWCNTs content was 2 wt% for a thickness of 3 mm, resulting in a reflection loss of −28 dB, refers to the largest reflection loss achieved at 9 GHz.

Soybean-based memristor for multilevel data storage and emulation of synaptic behavior

Electronic devices based on biological materials have shown great application potential in many fields, so they have become a hot topic of research. In this paper, biomaterial soybean and one-dimensional nanomaterial multiwalled carbon nanotubes (MWCNTs) were mixed as the active layer to fabricate Al/soybean MWCNT/ITO/glass memristor devices. The device shows a bipolar resistive switching characteristic, and the retention time exceeds 104 s. By adjusting the concentration of MWCNTs, the ON/OFF current ratio can be modulated in the range of 1–104, and the endurance of the device is enhanced by increasing the MWCNT concentration. By changing the compliance current, the device can realize multilevel storage and improve the storage density. The write-read-erase-read process can still be completed under low voltage (±2 V), which opens up a new way for the fabrication of low power consumption memristor devices. In addition, the device successfully simulates the potentiation and suppression behavior of biological synapses, showing promise for making new breakthroughs in the field of implantable neural system research for biological memristor-based artificial synapses.

The Effect of Multi-Walled Carbon Nanotubes on the Heat-Release Properties of Elastic Nanocomposites

Of great importance in materials science is the design of effective functional materials that can be used in various technological fields. Nanomodified materials, which have fundamentally new properties and provide previously unrealized properties, have acquired particular importance. When creating heating elements and materials for deformation measurement, it is necessary to understand the patterns of heat release under conditions of mechanical deformation of the material, as this expands the potential applications of such materials. A study of elastomers modified with multi-walled carbon nanotubes (MWCNTs) has been carried at the MWCNTs concentration of 1–8 wt.%. The modes of heat release of nanomodified elastomers at a voltage of 50 V at different levels of tension are reported. The increment of the MWCNTs concentration to 7 wt.% leads to an increment in the power of heat emissions. It is worth noting the possibility of using the obtained elastomer samples with MNT as sensitive elements of strain sensors, which will allow obtaining information about physical and chemical parameters following the principles of measuring the change in electrical resistance that occurs during stretching and torsion. The changes in conductivity and heat emission under different conditions have been studied in parallel with Raman mapping and infrared thermography. The reported studies allow to make the next step to develop flexible functional materials for the field of electric heating and deformation measurement based on elastic matrices and nanoscale conductive fillers.

Fabrication of multiwalled carbon nanotube‐reinforced rapeseed‐oil‐based polyurethane coatings for anticorrosive applications

AbstractThis work describes the synthesis of a hydroxy‐terminated oligomer for polyurethane preparation (HTO‐PU) from rapeseed oil, salicylic acid and toluene diisocyanate. HTO‐PU was further incorporated with different amounts of multiwalled carbon nanotubes (MWCNTs) to produce HTO‐PU@MWCNT nanocomposites. These nanocomposites were then converted to coatings using mild steel strip as a substrate and allowed to cure at room temperature. Fourier transform infrared and NMR spectroscopic techniques were used for structural elucidation. Surface morphology was determined using scanning electron microscopy and X‐ray photoelectron spectroscopy. Thermal stability (&gt;300 °C) of these coatings was evaluated through thermogravimetric analysis and differential scanning calorimetry. Contact angle values suggest that incorporation of MWCNTs enhanced the hydrophobicity of HTO‐PU coatings. Physicomechanical results reveal that these coatings are highly glossy, scratch resistant and impact resistant possessing good adhesion and excellent pencil hardness. The optimum concentration of MWCNTs was found to be 1.0 wt. %, below and above which the coating performance was observed to deteriorate. The corrosion resistance and barrier properties of these coatings were examined using electrochemical impedance spectroscopy, the results of which suggest excellent corrosion inhibition efficiency of HTO‐PU@MWCNT‐1.0 coatings until 28 days. This study suggests a step towards synthesis of MWCNT‐incorporated green PU coatings for protective applications. © 2022 Society of Industrial Chemistry.

Carbon Nanotube Migration in Melt-Compounded PEO/PE Blends and Its Impact on Electrical and Rheological Properties.

In this work, the effects of MWCNT concentration and mixing time on the migration of multi-walled carbon nanotubes (MWCNTs) within polyethylene oxide (PEO)/polyethylene (PE) blends are studied. Two-step mixing used to pre-localize MWCNTs within the PE phase and subsequently to observe their migration into the thermodynamically favored PEO phase. SEM micrographs show that many MWCNTs migrated into PEO. PEO/PE 40:60 polymer blend nanocomposites with 3 vol% MWCNTs mixed for short durations exhibited exceptional electromagnetic interference shielding effectiveness (EMI SE) and electrical conductivity (14.1 dB and 22.1 S/m, respectively), with properties dropping significantly at higher mixing times, suggesting the disruption of percolated MWCNT networks within the PE phase. PE grafted with maleic anhydride (PEMA) was introduced as a compatibilizer to arrest the migration of MWCNTs by creating a barrier at the PEO/PE interface. For the compatibilized system, EMI SE and electrical conductivity measurements showed a peak in electrical properties at 5 min of mixing (15.6 dB and 68.7 S/m), higher than those found for uncompatibilized systems. These improvements suggest that compatibilization can be effective at halting MWCNT migration. Although utilizing differences in thermodynamic affinity to draw MWCNTs toward the polymer/polymer interface of polymer blend systems can be an effective way to achieve interfacial localization, an excessively low viscosity of the destination phase may play a major role in reducing the entrapment of MWCNTs at the interface.

Fabrication and Characterisation of MWCNT/Polyvinyl (PVC) Polymer Inclusion Membrane for Zinc (II) Ion Removal from Aqueous Solution.

Heavy metal pollution has prompted researchers to establish the most effective method to tackle the impacts of heavy metals on living things and the environment, which include by applying nanoparticles. An example is the employment of multi-walled carbon nanotubes (MWCNTs) as an additive in an intermediate membrane or polymer inclusion membrane (PIM). The MWCNTs were added to enhance the properties and reinforce the transport performance of zinc (II) ion (Zn2+) removal from the source phase to the receiver phase by the PIMs. The present study constructed a membrane with a poly(vinyl chloride) (PVC)-based polymer, dioctyl phthalate (DOP) plasticiser, and bis-(2-ethylhexyl) phosphate (B2EHP) carrier incorporated with different concentrations of MWCNTs. The contact angle (CA), water uptake, ion exchange capacity (IEC), and porosity of the fabricated membranes were evaluated. The membrane was also characterised by employing scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and electrochemical impedance spectroscopy (EIS). Subsequently, the fabricated PIM (W1) and mixed matrix (MM)-PIM (W2–W5) samples were assessed under different parameters to acquire the ideal membrane composition and effectiveness. Kinetic modelling of Zn2+ removal by the fabricated PIMs under similar conditions was performed to reveal the mechanisms involved. The average removal efficiency of the membranes was >99% at different parameter conditions. Nevertheless, the W3 membrane with 1.0 wt% MWCNT immersed in a 5 mg/L initial Zn2+ concentration and 1.0 M receiver solution for seven hours at pH 2 demonstrated the highest percentage of Zn2+ removal. The experimental data were best fitted to the pseudo-first-order kinetic model (PFO) in kinetic modelling, and the permeability and flux of the W3 at optimum conditions were 0.053 m s−1 and 0.0532 mol m−2 s−1, respectively. In conclusion, the transport mechanism of Zn2+ was enhanced with the addition of the MWCNTs.

Effect of X-ray exposure on nano-mechanical properties of multi-walled carbon nanotube incorporated silicone polymer nanocomposites: An AFM-based study

Nano-mechanical properties of silicone polymer-based nanocomposites loaded with multi-walled carbon nanotube (MWCNT) as nanofillers are probed here using the atomic force microscopy (AFM) technique. Further, the effects of MWCNT concentration and X-ray exposure on the nano-mechanical and topographic properties of the polymer nanocomposites are systematically studied. The root mean square surface roughness is found to increase by ∼123% when the neat polymer matrix is loaded with 2.5 wt.% of MWCNT, whereas, for a fixed MWCNT concentration, the surface roughness is found to increase by ∼171% after X-ray irradiation. This is attributed to the X-ray induced polymer degradation, polymer pull-out and poor filler-matrix interaction leading to the aggregation of MWCNT. Adhesion force and adhesion energy are estimated from the AFM-based force-displacement curves. Both quantities are found to increase with MWCNT concentration. After an exposure to diagnostic X-rays (30–70 keV), the adhesion force is found to increase by ∼4 times, which is attributed to the increased tip-surface contact area due to the higher surface roughness of the X-ray exposed samples. Further, the variation of adhesion energy with filler concentration is found to be in agreement with the theoretical values obtained from the Johnson, Kendall and Roberts (JKR) model. The elastic modulus is found to increase with the filler concentration due to an increase in adhesion force. The obtained results are beneficial for the optimal design of nanofiller loaded polymer nanocomposites for various applications, including the fabrication of lead-free radio-opaque nanocomposites.